Abstract Triaxial compression experiments on dry Ottawa sand are numerically simulated using Finite Discrete Element Method (FDEM) in conjunction with X-ray CT imaging. A novel framework is introduced and validated where particle shape is captured in FEM simulations using shell elements for simulating triaxial boundary value problem. The proposed approach is well suited for load cases with low/intermediate confining pressures where particle breakage is negligible. The numerical model allows for grain deformation as well as robust particle contact fabric evolution for the realistic grain morphology. For this research, the confining latex membrane is modelled as hyper-elastic material to provide flexible boundary condition on the lateral surface of the cylindrical sand specimen. Volume change measurements are obtained directly based on the convex hull of an assembly of sand grains, with no contributions or associated errors from latex membrane effects. In this paper, we attempt to explore the FDEM modeling aspect from different perspectives considering macroscale and microscale response. The influence of the frictional and frictionless boundary on the strength deformation response and localization in displacement field is discussed. Furthermore, sensitivity of mesh refinement, interparticle friction coefficient and critical shear stress on strength and volume change response is quantified.

中文翻译：

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使用 FDEM 和显微 X 射线计算机断层扫描在沙子中进行三轴压缩

摘要 使用有限离散元法 (FDEM) 结合 X 射线 CT 成像对干燥的渥太华沙子进行三轴压缩实验进行数值模拟。引入并验证了一种新框架，其中使用壳单元在有限元模拟中捕获粒子形状以模拟三轴边界值问题。所提出的方法非常适合具有低/中围压的载荷情况，其中颗粒破损可以忽略不计。数值模型允许颗粒变形以及真实颗粒形态的稳健颗粒接触织物演化。在这项研究中，限制乳胶膜被建模为超弹性材料，以在圆柱形砂试样的侧面提供灵活的边界条件。体积变化测量直接基于砂粒组合的凸包获得，没有乳胶膜效应的贡献或相关误差。在本文中，我们尝试从宏观和微观响应的不同角度探索 FDEM 建模方面。讨论了摩擦和无摩擦边界对位移场中强度变形响应和定位的影响。此外，量化网格细化、粒子间摩擦系数和临界剪切应力对强度和体积变化响应的敏感性。我们试图从宏观和微观响应的不同角度探索 FDEM 建模方面。讨论了摩擦和无摩擦边界对位移场中强度变形响应和局部化的影响。此外，量化网格细化、粒子间摩擦系数和临界剪切应力对强度和体积变化响应的敏感性。我们试图从宏观和微观响应的不同角度探索 FDEM 建模方面。讨论了摩擦和无摩擦边界对位移场中强度变形响应和定位的影响。此外，量化网格细化、粒子间摩擦系数和临界剪切应力对强度和体积变化响应的敏感性。